Solar power is now cheaper than the grid in hundreds of Chinese cities

London(CNN Business) Solar energy in hundreds of Chinese cities is now cheaper than electricity supplied by the national grid, and it can even compete with coal-fired power in 75 of them, a new study has found.

Some 344 Chinese cities were found to have solar systems producing energy at lower prices than the grid, without any subsidies, according to the research published in the journal Nature Energy. That could encourage further investment in renewable energy, according to the authors.

China has made huge progress in developing solar projects and pledged to invest 2.5 trillion yuan ($367 billion) in renewable power generation — solar, wind, hydro and nuclear — from 2017-2020.

Solar can also compete on price with electricity produced solely from coal in around 22% of these cities, according to the research team led by Jinyue Yan from the Royal Institute of Technology in Stockholm, Sweden.

China has long relied on coal to meet its energy needs, but has started to close mines and restrict the construction of new coal power plants in recent years, particularly in heavily polluted regions. Nevertheless, it still accounts for 59% of the country's consumption, according to Reuters.

The researchers said that cheaper prices "may encourage a substantial uptake of industrial and commercial solar systems in China in the near future."

China is also driving down solar prices around the world thanks to the scale of production and learning curve effects, according to Sam Geall, a China climate and energy expert at Chatham House.

"For China, this is mainly driven by national self-interest: the government sees that solar power can help the country enhance energy security and resilience, mitigate urban air pollution, and position the country as the world's leading supplier of the clean technologies of the future," Geall told CNN.

"The economic dynamism of solar in cities in China should provide even more reason to boost deployment, which is a positive sign for China's climate ambitions and therefore the world's."

And there are already ambitious plans in the pipeline, including a solar energy plant in space that could one day beam enough power back to Earth to light up an entire city.

The state-owned China Aerospace Science and Technology Corporation hopes to be operating a commercially viable solar space station by 2050, according to a recent report in the country's official newspaper Science and Technology Daily.

A Chinese firm also built the world's largest concentrated solar farm, the Noor-Ouarzazate complex in Morocco.

More than 3,000 hectares (7,400 acres) in area — the size of 3,500 football fields — it produces enough electricity to power a city the size of Prague, or twice the size of Marrakesh.

However, concerns have been raised over the green credentials of the solar energy industry.

While they may produce energy with fewer emissions, the growing amount of panel waste is a concern.

China alone is set to produce 20 million tons of solar panel waste by 2050, according to a 2016 estimate from the International Renewable Energy Agency (IRENA).

And Chinese solar panel manufacturers have faced protests from locals who accuse them of mishandling hazardous waste.

In 2011, Jinko Solar Holding Co apologized for dumping toxic waste following violent protests sparked by the death of large numbers of fish in a nearby river, Reuters reported.